News Feature

Green crabs inside a lobster trap, hauled by participants in Stonington’s green crab survey in November of 2013.

Photo courtesy of Carla Guenther

by
Anne Berleant

Green crabs have called the coastal waters of Maine home since the 1950s, but the recent, extreme rise in numbers has had a negative effect on clam and other shellfish populations, eelgrass beds and the balance of the coastal marine ecosystem.

The Maine Department of Resources has responded with an emergency rule change aimed at “improv[ing] the ability of individuals to collect and remove from coastal Maine waters the invasive and damaging green crab species,” according to its summary. The rule took effect on August 10.

“[Green crabs] eat everything,” said Susan Shaw, executive director of Marine Environmental Research Institute in Blue Hill, speaking at the annual meeting of the Friends of Blue Hill Bay in July. “Mussel beds are disappearing.”

A single female crab breeds two to three times each year, laying as many as 165,000 eggs each time, according to Shaw. MERI is involved in monitoring green crabs in Penobscot Bay—part of a wider effort by the DMR—and has trapped “thousands” this summer.

Green crabs are native to Europe but began appearing on American shores since the Civil War, according to DMR marine scientist Brian Beal. They were first seen in Maine in the 1950s, with warmer waters in winter thought responsible for the huge rise in numbers in the last two to three years. Green crabs have no natural predators in the Gulf of Maine.

How the DMR rule change will help

Licensed commercial lobstermen may now keep green crabs caught as byproduct of lobster fishing, and licensed crab and lobster fishermen no longer need a green crab license in order to sell green crabs. Previously, green crabs caught by fishermen not owning a green crab license were limited to discarding the crabs or using them as bait or fertilizer.

“There is no [market for green crabs] that I’m aware of right now,” DMR Assistant Commissioner Meredith Mendelson said in a recent telephone call.

However, according to the DMR, private efforts are under way to convert green crabs for use as aquaculture feed and for compost. (See maine.gov/dmr/rm/invasives/GreenCrabs.htm.)

In addition, reporting on green crab harvests to the DMR are no longer required by licensed or unlicensed fishermen.

Individuals may now use traps to “take, possess or transport” green crabs for personal use without a license; previously, catching by trap was prohibited. Municipalities are still exempt from licensing requirements for all uses with an approved Municipal Green Crab Exemption from the DMR under state statute.

The regulation changes followed a “green crab summit” held in December 2013 by the DMR, Maine Sea Grant, the Maine Coastal Program and the U.S. Geological Survey and a July 14 public hearing held by the DMR.